This invention relates to a smoke-producing pyrotechnic composition and its applications.
The field of art is that of pyrotechnics and more particularly means for producing colored smokes.
A great deal of research has been undertaken in this field in order to obtain an efficient result from such compositions, that is to say to obtain the sublimation of the coloring substance contained in the composition which, upon condensation in the atmosphere, produces the effect of colored smoke.
It is known that the following problems arise;
the coloring substance is chemically unstable and must be able to be preserved in its greater part,
the resins must be combustible at low temperature in order to make the sublimation of the coloring substance easier;
the residues coming from this combustion must not be too abundant or compact, as in such case the "occlusion" of the coloring substance is brought about;
the coloring substances have active chemical functions capable of inhibiting the polymerization of numerous resins.
The purpose which is to be achieved is therefore a rapid sublimation of the coloring substance at low temperature, at which temperature the composition is combustible without leaving excessively compact or abundant residues.
Composition have been proposed that contain binders of plastic in order to improve the coherence of the charge and form a consolidated mass. They have never actually been used as the colored-smoke effect is generally poor.
Other compositions have the drawback of burning at temperatures which are too high or leave too many carbonaceous residues which are impermeable to the gases, causing the destruction of the components and therefore poor effectiveness in the production of colored smokes. Another drawback may be the rapid ascent of the smoke which then does not last sufficiently long.